Safe can be used if someone gave you sum ting or done someting for you,you can also use it as a thank you & when ur leaving someone or somewhere you can say safe.you can use it as good-bye.Safe.the word safe can be used in 3 terms

Hello
Goodbye
Good morning
Good night
Good afternoon
good evening
Thank you
Nice/Friendly/Decent
Good/Quality/Fun
Awesome/Brilliant/Great
Secure
A place to deposit goods of value securly, which keeps them 'Safe'.